HD64F38024HV Datasheet, PDF (132/684 Pages) Renesas Technology Corp – Hardware Manual Renesas 8-Bit Single-Chip Microcomputer H8 Family/H8/300L Super Low Power Series

Section 4 Clock Pulse Generators
External Clock Input Method
Connect an external clock signal to pin OSC₁, and leave pin OSC₂ open. Figure 4.7 shows a
typical connection.
OSC₁
OSC₂
Open
External clock input
Frequency
Duty cycle
Figure 4.7 External Clock Input (Example)
Oscillator Clock (φOSC)
45% to 55%
On-Chip Oscillator Selection Method (H8/38124 Group Only)
The on-chip oscillator is selected by setting the IRQAEC pin input level during resets.* Table 4.3
lists the methods for selecting the system clock oscillator and the on-chip oscillator. The IRQAEC
pin input level set during resets must be fixed at V_CC or GND, based on the oscillator to be
selected. It is not necessary to connect an oscillator to pins OSC1 and OSC2 if the on-chip
oscillator is selected. In this case, pin OSC1 should be fixed at V_CC or GND.
Note:
The system clock oscillator must be selected in order to program or erase flash memory as
part of operations such as on-board programming. Also, when using the on-chip emulator,
an oscillator should be connected, or an external clock input, even if the on-chip oscillator
is selected.
* Other than watchdog timer or low-voltage detect circuit reset.
Table 4.3 System Clock Oscillator and On-Chip Oscillator Selection Methods
IRQAEC pin input level (during resets)
System clock oscillator
On-chip oscillator
0
Enabled
Disabled
1
Disabled
Enabled
Rev. 8.00 Mar. 09, 2010 Page 110 of 658
REJ09B0042-0800